CVE-2021-29536 Explained : Impact and Mitigation

TensorFlow is an end-to-end open source platform for machine learning. An attacker can exploit a heap buffer overflow vulnerability in

QuantizedReshape

by providing invalid thresholds for quantization. This vulnerability exists in versions of TensorFlow prior to 2.5.0. The issue arises due to the assumption that certain arguments are always valid scalars, leading to potential heap overflow. TensorFlow has addressed this issue in version 2.5.0 and plans to patch affected versions from 2.1.4 to 2.4.2.

Understanding CVE-2021-29536

This section provides insights into the nature of the vulnerability identified as CVE-2021-29536.

What is CVE-2021-29536?

CVE-2021-29536 is a heap buffer overflow vulnerability in

QuantizedReshape

within TensorFlow. The flaw allows an attacker to trigger a heap overflow by providing malicious input during quantization threshold processing.

The Impact of CVE-2021-29536

This vulnerability could be exploited by a local attacker to execute arbitrary code or crash the application, potentially leading to denial of service conditions. However, the confidentiality and integrity of the system are not compromised.

Technical Details of CVE-2021-29536

In this section, we delve into the technical aspects of CVE-2021-29536.

Vulnerability Description

The vulnerability arises due to improper validation of input thresholds for quantization in TensorFlow's

QuantizedReshape

. If a tensor is empty, accessing the element at position 0 results in a heap buffer overflow.

Affected Systems and Versions

The affected versions of TensorFlow include:

TensorFlow < 2.1.4
TensorFlow >= 2.2.0, < 2.2.3
TensorFlow >= 2.3.0, < 2.3.3
TensorFlow >= 2.4.0, < 2.4.2

Exploitation Mechanism

The vulnerability can be exploited by passing in specially crafted input that includes invalid thresholds for quantization, triggering a heap buffer overflow in the

QuantizedReshape

function.

Mitigation and Prevention

This section outlines the steps to mitigate and prevent the exploitation of CVE-2021-29536.

Immediate Steps to Take

Users are advised to update TensorFlow to version 2.5.0 to address this vulnerability. For users on affected versions, security patches will be provided by TensorFlow for versions 2.1.4 to 2.4.2.

Long-Term Security Practices

To enhance system security, users should regularly update TensorFlow to the latest stable release and follow best practices in secure coding and input validation.

Patching and Updates

Keep track of security advisories from TensorFlow and apply patches promptly to ensure that your system is protected against known vulnerabilities.